LDAP error when logging into the Rancher UI after a Rancher upgrade

Article Number: 000020985

Situation

After upgrading Rancher to version 2.6.9 or higher, the following error is seen after logging into the Rancher UI:

ldap error Error creating ssl connection: LDAP Result Code 200 "Network Error": tls: server selected unsupported protocol version 301

Cause

This problem happens when the LDAP server used for authentication with Rancher uses a version of TLS lower than 1.2.
Rancher 2.6.9 uses Go 1.19 where the crypto/tls library that is used requires a minimum version of TLS 1.2 for LDAP connections.

Resolution

Upgrade the version of TLS that the LDAP server uses to at least 1.2.